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July, 07/27/2015
Events and times subject to change

July 31, 2015 Friday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

Informal Astro Talk
Ken Wong

The Innermost Mass Distribution of the Gravitational Lens SDP.81 from ALMA Observations

he central image of a strongly lensed background source places constraints on the foreground lens galaxy's inner mass profile slope, core radius and mass of its nuclear supermassive black hole. Using high-resolution long-baseline ALMA observations and archival HST imaging, we model the gravitational lens SDP.81 and search for the demagnified central image. There is central continuum emission from the lens galaxy's AGN but no evidence of the central lensed image in any molecular line. We use the CO maps to determine the flux limit of the central image excluding the AGN continuum. We predict the flux density of the central image and use the limits from the ALMA data to constrain the inner mass distribution of the lens. For the core radius of 0.15" measured from HST photometry of the lens galaxy assuming that the central flux is completely attributed to the AGN, we find that a black hole mass of log(M_BH/M_sun) > 8.5 is preferred. Deeper observations with a detection of the central image will significantly improve the constraints of the inner mass distribution of the lens galaxy.


August 4, 2015 Tuesday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

Informal Astro Talk
Iair Arcavi
LCOGT / UC Santa Barbara

The First Optical Sample of Tidal Disruption Events and Their Surprising Host Galaxy Preference

A star passing close to a super-massive black hole can be torn apart in a tidal disruption event (TDE). Such events may be accompanied by optical/UV flares, and can thus be used to study otherwise quiescent distant black holes. But TDEs are rare and, until recently, very few candidate flares were convincingly identified in observations. I will present three TDE candidates we recently discovered in Palomar Transient Factory data. Analyzing their observed properties together with those of candidates from the literature, we unify them, for the first time, into a single class of transients on a continuous scale of spectral characteristics. In addition, we find that most TDE candidates in our sample occur in rare E+A-like hosts (possible post-merger galaxies). This surprising result may hold important clues about the conditions favored by TDEs. Events similar to those we identified are now being discovered by various surveys at an increasing rate, igniting a flurry of theoretical work to try and interpret the observed properties. It seems we're now entering a period of rapid advancement in our understanding of how to find, observe and explain these intriguing transients.


September 18, 2015 Friday 11:00 AM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

Informal Astro Talk
Matteo Biagetti
University of Geneva

TBA



October 2, 2015 Friday 11:00 AM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

Informal Astro Talk
Ting-Wen Lan
Johns Hopkins University

Diffuse Interstellar Bands or Mg II absorbers



October 2, 2015 Friday 3:00 PM  +
Columbia University
Other CCPP (ccpp)

Big Apple Colloquium
Tremaine Merritt
IAS & RIT

Debate: The Final Parsec Problem

Can two super-massive black holes in a galactic nucleus merge in a Hubble time?


October 16, 2015 Friday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars (astro)


Schuyler Dyk
IPAC/Caltech



November 20, 2015 Friday 12:00 PM  +
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars (astro)


Charlie Conroy
Harvard University



November 20, 2015 Friday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars (astro)